This invention relates generally to an improved electrical connector strain relief system and, more particularly, to an improved cable clamp secured to a mounting flange of the connector housing for resisting bending of the flange due to tension applied to a cable held by the clamp.
Many types of strain relief systems have been devised for use with multicontact electrical connectors terminating multiconductor cables. The present invention concerns an improved strain relief system which is particularly suited for use with multicontact connectors employed in the telecommunications field, such as Bunker Ramo Corporation's 57 SERIES and 157 SERIES electrical connectors. A representative one of these types of connectors typically comprises a two-piece, elongated, metallic shell, a dielectric insert housed within the shell, and a plurality of miniature, insulation piercing contacts along the elongated edges of the insert for terminating the individual conductors of the cable. Flange portions protruding from opposite ends of both shell pieces are fastened face-to-face to secure the shell pieces together and provide two-piece mounting flanges at both ends of the connector.
Because the cable terminated by the connector is often subjected to tugging and twisting which, left unchecked, can result in impairment of the individual conductor terminations in the connector, especially when the connector is not mounted on a support structure or otherwise supported, numerous strain relief systems have been devised to isolate the connector terminations from such forces. The majority of the designs which have been suggested and utilized in the past for this purpose fall into the following broad categories: (a) cable clamps which are attached to or form a part of a protective hood covering the connector; (b) cable clamps which rely on cooperation between such a hood and the connector housing; and (c) cable clamps which are attached to the mounting flange at one end of the connector.
The present invention is concerned with the last category of clamp designs, which function without assistance or interference by the connector hood. Typically, these clamps have comprised a base portion attached to the mounting flange by a rivet or the like and a cable gripping portion elevated with respect to the base portion for holding the cable securely relative to the connector. Although such flange mounted clamps offer many advantages due to other design considerations, the steel mounting flange is thin, e.g., each of the two shell flange portions comprising the mounting flange being only about 0.016 inches thick, and the two-piece mounting flange has been found to bend when pull-out forces as low as 16 pounds are applied to the cable. Thus, while the cable clamp is intended to provide strain relief, the deformation of the mounting flange, and the resultant displacement of the clamp with respect to the connector, may cause the clamp itself to pull the conductors from their contacts, thereby impairing the reliability of the terminations and hence the reliability of the connector.